A Brake Diaphram

[dalej]

Great photos and post Joe!

[BrianE]

Great post Joe. This points out the fact that when updating chassis components there is no real need to install brand new brake chambers. For the hands on folks, they come apart easily and are easily overhauled. One must be very careful however when disassembling the emergency dual brake chambers.

[phorner]

Great post, Joe.

But I gotta ask.....

Which job is dirtier.....tearin' em apart to re-build?..... or replacin' em?

[Joe Cannarozzi]

Paul, Paul, Paul.

I can't believe you even asked that question.

I could not have been more surprised to crawl under what I defined as one of the best looking and well kept Liberty's in the club (yours), only to emerge dirtier than I have ever gotten on anyone's yet,and 2 days in a row.

Then to add insult to injury you give me hand cleaner with enough grit to rip the first 2 layers of skin off prepping me for the burn of the gasoline you then handed me, and we hear complaints about water-boarding, sheesh.

P1051033[2] (2).JPG

I could not get this dirty working on our bus if I tried and it is 15 years older than yours.

In answer to your question I guess it depends on whos I'm working on

[phorner]

I hear ya, Joe....

Was pretty surprized myself to see how much grime one (apparently clean) bus can deposit on a guy. I think the Liberty just enjoyed your touch so much she insisted on leaving her mark

It was fun though.......

[Joe Cannarozzi]

If you do decide to just replace a diaphragm NEVER NEVER remove the clamp on a chamber with 2 sets of them.

NEVER .

Putting it another way if the chamber has only 1 air line going to it you are safe, If it has 2 air lines going to the chamber LEAVE IT TO SOMEONE WHO IS SURE WHAT THEY ARE DOING. If you pull the wrong clamps on a chamber with 2 sets of clamps it could kill you.

Here is all it takes to relieve the tension from the spring on that SERVICE BRAKE diaphragm so you can switch it.

I have finished up with the steer axle and I neglected showing some important steps that I can demonstrate with the tag.

Simultaneously take a large screwdriver shove it in the cleaves of the slack adjuster and pull back with one hand (just like you were checking slack) and with your other hand clamp the push rod with some vice grips right at the housing so it can't spring back
my bus 073.jpg

my bus 074.jpg
Now when the 2 clamps are removed the tension is gone.

The 2 diaphragms on the steer were dated 1981 so that means they were not only original but sat on a shelf for 4 years before they were used. The new ones I'm installing were manufactured in 07. No good Mr. Parts guy, no good. I expect my parts deli fresh, thank you.

[Jon Wehrenberg]

Joe has spoken the gospel with respect to monkeying around with combo brake chambers. The spring brake portion of those brakes are under considerable pressure when not caged. However, only the older combo brakes can be serviced anymore. The spring brake portion (the emergency brake part of the combo) is permanently assembled on newer models. I don't know when the change was made but they cannot be disassembled.

I have had a brake diaphragm failure and it was not from an aging rubber that cracked and failed, but instead was the result of a poor finish on the head of the plunger that the diaphragm pushes against. Apparently from driving in the snow belt the corrosion caused by all the salt created a rough surface that wore through the rubber creating a weak spot that failed. The failure was on the emergency brake diaphragm, and at the time I was able to rebuild the brake as Joe showed, but the spring had been caged using the T bolt supplied with the brake.

It is not the age of the diaphragm that is likely to be the problem, but the quality of the inside of the chamber. If there is any corrosion, change the chamber, not the diaphragm.